1. Field of the Invention
The present invention relates to apparatus and method for checking insulation of a cell module assembly composed of a plurality of pouch cells and a probe for the same. More particularly, the present invention relates to apparatus and method for rapidly checking and determining insulation of the entire cell module assembly by means of a probing means such as a probe electrically contactable with all of the plurality of pouch cells, and a probe for the same.
2. Description of the Related Art
A cell module assembly is an assembly composed of a plurality of pouch cells. The pouch cell has a battery cell therein, and a polymer wrapping corresponding to a pouch is provided to surround the battery cell.
Referring to FIG. 1 that is a perspective view showing an appearance of a pouch cell and FIG. 2 that is a sectional view taken along the line A-A′, a pouch cell 100 includes electrodes 110, a pouch 120 and a battery cell 130.
To make such a pouch cell 100, as shown in FIG. 3, a pouch material having a predetermined size capable of wrapping the battery cell 130 is adhered to upper and lower portions of the battery cell 130.
The pouch 120 protects the battery cell 130 and is configured as an aluminum film so as to complement electric chemical properties of the battery cell 130 and improve thermal resistance thereof. Also, in order to ensure insulation of the battery cell 130 from the outside, the aluminum film is coated with an insulating material such as PET (polyethylene terephthalate) resin or nylon resin.
In case upper and lower pouches are bonded to configure the pouch as shown in FIG. 3, CPP (casted polypropylene) or PP (polypropylene) may be used for adhesion between the upper and lower pouches. In this case, as shown in FIG. 4, the sealing surface serving as an outer periphery used for adhesion of the pouch 120 has insulating layers 121, aluminum films 123 and an adhesive layer 125.
In case the inner structure of the pouch cell 100 is broken or damaged due to an external impact to destroy insulation of the pouch cell 100, the battery cell cannot maintain a normal voltage but may cause low voltage, which may result in swelling of the inner battery cell.
This may cause consecutive problems such as explosion of the battery cell, which is fatal to a user or mounted equipment, so it is preferred to thoroughly check the insulation of the pouch cell 100 and thus fundamentally eliminate inferiority.
FIG. 5 shows a cell module assembly 200 composed of a plurality of pouch cells configured as above, and the cell module assembly 200 is a battery module in which a plurality of pouch cells 100 as above are connected in series. A portion of the pouch cell 100 corresponding to the electrode 110 (see FIG. 1) is electrically contacted to an electrode 210 provided at the cell module assembly 200, and the pouch 120 of each pouch cell 100 is partially exposed out.
FIG. 6 illustrates an apparatus for checking an insulation resistance of the cell module assembly, which is generally used conventionally. As shown in FIG. 6, one probing unit 310 is electrically contacted to the electrode 210, and another probing unit 320 is electrically contacted to the aluminum film 123 of the pouch, exposed out. After that, electric characteristic values of both probing units 310, 320 are measured.
In the above method, a probing unit should be contacted to the aluminum film 123 so as to measure insulation. However, the probing unit 320 is point-contacted with the aluminum film 123, which cannot ensure reliable contact. In addition, if a force is applied for better physical contact between the probing unit 320 and the aluminum film 123, the outer periphery of the pouch may be easily deformed without enduring the applied force due to its material properties, so it is not easy to maintain the physical contact for electric connection between the probing unit 320 and the aluminum film 123, which makes it difficult to perform the checking work.
In addition, the cell module assembly is generally composed of a plurality of cells, and the plurality of cells should be measured one by one so as to determine insulation of the cell module assembly itself, which consumes a lot of time as much as the number of cells.
As a result, the insulation test for the pouch cell does not ensure reliability due to the above general conditions, and a lot of time is consumed for the checking work. Thus, it is difficult to remove inferior cells or inferior cell module assemblies, and the appearance of the pouch may be easily broken. In addition, the above method may be an obstacle in automating the insulation checking work due to the above problems.